Circular arc-forming device



Mal'. 20, 1928.

R. F. LAFLER.

CIRCULAR ARC FORMING DEVICE.

2 SHEETS-SHEET l- FILED MAY 5.1921.

III

Mar. 20, 1923.

2 SHEE.TS-SHEET 2.

FILED MAY 6.1921- R F LAFLER mRcuLAH ARC FoRMlNG DEVICE.

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Patented ar.. 2d, i923.

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application :ned may e, 1921. serai ne. 467,421.

To all whom it may conce/1m:

Be it known that I, RAYMoND F. LArLnn, a citizen of the United States,and a.' resident of Syracuse, inthe coi'lnty of Qnondaga, in the Stateof New York, have invented new and useful Improvements in Circular Arc-Forrning Devices, of which the following, taken in connection with theafccoinim-nyjingdrawings, is a full. clear, and exact description.

rlhis invention relates toa circular arc forming device adapted to heused in connection with lathes and analogous machines for generating orproducing spherical or cylindrical (either convex or concaye)` surfacesof widely varying radii from infinity to relatively short radii, and isparticularly useful in the formation of laps commonly used in grindingof lenses, although it is evident that the same device may be used formany other purposes requiring the formation oi cylindrical or sphericalcontours.

The invention is based upon the geometrical principle that if an angleequal to or greater than a right angle is shifted so that its straightsides ride against two points in the circumference of a. circle of givenradius, the vertex of that angle will describe an arc of a circle ofthat radius, and the main oliject of my invention is to attach atoolholder to the vertex of a straight edge angle ot the charactermentioned in such manner that the tool will be caused to describe a truecircular arc of the same radiiis as that. described by the vertex" ofthe angle as the ter is shifted against the circumferential pointsreferred to. y

In other words, l have sought to provide means for shifting thetool-holder radially or transversely of the axis of the work tosimultaneously shift the angle i'n the same direction, and at the sametime to utilize the straight sides'of the angle and circumferentialbearing points therefor for imparting the desired inoven'ient of thetool-holder axially of the work to cause the tool to produce the desiredcircular contour upon' said work. u

A further object is to provide means for simultaneously adjusting theopposite sides of the angle to vary said angle to any degree froinaright angle to a straight line and 90 degrees beyond through a range ofsubstantially 270 degrees so that the same device may be employed toproduce circular convex or concave contours of any radius to infinity. yl

Other objects and uses relating to specific `parts of the device will bebrought out in the following description:

ln the drawings: I

Figure l is a top plan of a circular arc forming device embodying thevarious features of my invention, adjusted to produce spherical,cylindrical or convex surfaces upon the work.

u Figure 2 is a longitudinal vertical sectional view of the same devicetaken on line 2 2, Figure 1.

Figures 3 and are transverse verticalsectional views of the samemachine, enlarged, taken on lines 3 3 and 4 4, Figure l.

Figure `5 is an enlarged detail sec-tional view taken on line 5 5,Figure i.

Figure 6 is a enlarged transverse vertical sectional view taken on line6 6, Figure l.

Figures 7; 8 and 9 are enlarged detail sectional views taken,respectively,y on lines 7 7, 3 8 and Figure l.

Figure 10 is a detail sectional view partly inelevation, showing`ainodiiied form of tool for forming cylindrical surfaces.

The arc forming device isv shown as mounted upon and movable along' thebed of a lathe having, a work-holder B mounted upon the head stock L anddriven by a motor Q through the medium ot pulleys c and and a belt Esaid device being set for producing convex contoursA upon the work as ltThe lathe bed lt is provided with lengthwise dove-tailed ways gt along.Yand upon which are movable, s the rhead-stock Z a cross-block 1 and anintermediate cross head Q having dove-tailed grooves in their lowersides `for engagement with the ways fr-l, and also provided with theusual and. adjiusting lscrews for tali(- ing up wea'r and for lockingtheir corresponding parts"` in any Aposition of adjust- ,nient ifdesired. A y

The cross-block 1- i'sprov'ided with a dove-tailed guide groove 3extending transversely ot' and at right angles to the axis ag forreceiving a pair of dovet-ailed nuts -4-, which are located equaldistances from and at opposite sides ot the longitudinal center ot themachine and adjustable toward and from each other by means of ascrew-spindle -5- having right and lett hand threads engagingcorresponding apertures ot their respectivenuts Jfor adjusting thelatter equal distances in reverse directions at each turning movement ofthe screw.

One end ot the screw -5- is angular for receiving` a suitable wrench bywhich it may be rotated, and is also provided with spaced shoulders`--tS-` for engaging opposite faces of a lug on the cross-block -l tohold the spindle against endwise movement and thereby to hold the nuts-etd in their adjusted positions, the shoulder m6 at one side of the.lug` -JLA being adjustable aglialiy for permitting the removal andinsertion of the adjacent end of the spindle from and into the lug.

The nuts 4- are provided with upstanding bearing members 8- journal-edtherein to rot-ate about vertical in a plane at right angles to andequal distances from the longitudinal center ot the machine passing`through the axes ot the work-holder These bearing members 8- areprovided with flat diametrical bearing faces -8- adapted to be engagedby the edges of similar but opposed arms 9 9 which are pivoted to eachother and to a supporting member -10- by means ot a pivotal pin #llandeach is provided with opposite straight and parallel edges l2- and -l3-,one set of which as 12- is brought into engagement with the Vdat contactfaces -8- of the bearing members or pins -S- as may be necessary forproducing convexY or concave contours, the pivotal connection 11mbetween the arms -9- and their support 10- serving to permit said armsto be adjusted to different angles from a right angle to a substantiallystraight line and beyond to a reversely projecting' right angle orthrough an arc of substantially 270 degrees according as may benecessary for producing convex or concave contours of different radiifrom one-half the distance between the centers of the pins 8- toiniinity o1' straight lines as will be hereinafter more fully explained.

Suitable means is provided for adjusting the arms h9- to vary the anglebetween them, and for this purpose is provided a pair of links 14-pivotally connected at one end to the arms equal distances from andconnecting the pivot -11-, and having their opposite ends pivotallyconnected to each other by a pivotal bolt --15- which is Leashes movablein a lengthwise slot i6- in the supporting member -l0- and is held inits adjusted position against undue outward movement by an adjustingscrew -17- which is engaged in a threaded aperture --18- in the outerend wall of the slot -16- as shown in figure 2 and has its inner endengaged with the pivotal bolt -lthe inward movement of the pivotal pinl5 being prevented by the engagement oit the straight edges -lQ-W of thearms -9- with the flat faces --S- of the bearing pins S through themedium of the link connection -14-- The inner end of the support l0- ispivotally connected by a pivotal pin --19- to the outer end of alongitudinally movable plate -20- which in turn is movable along andupon a transversely movable carriage -f2l and is provided in its lowerside with a dove-tailed groove for receiving a dovetailed rib on theupper side of the carriage 21- to allow the plate 20- to moverectilinearly parallel with the axis of the work-support -B-.

The carriage 21- is movable transversely ot and upon the cross-head -2,and is vprovided at its under side with a dovetailed groove torreceiving a dove-tailed rib on the upper side o'l said crosshead,whereby the carriage with the sliding plate -20- thereon may be causedto move in a plane at right angles to the axis of the work-holder Thecarriage -21- is provided h a central pendent lug` movable in alengthwise or transverse slot Q3- in the cross-head 2 and provided witha threaded aperture for engagement by a screw spindle Q4-i, which isjournaled at one ond in a bearing -25- forming the adjacent end wall otthe slot -23 and is provided with collars *26- for engaging the oppositeends oi said bearing to hold the spindle against cndwise movement7 theouter end of said spindle being provided with a handle -27- by which thespindle may be rotated for adjusting the carriage -21- and plate 2Othereon transversely of the axis oi the work-holder iB- The adjacent'faces of the carriage 21- and superposed plate 20- are provided withcentral lengthwise grooves 2S- and 29- tor receiving a coil spring 80-having one end bearing against a shoulder -31- on the part 21- and itsother end engaged with a similar shoulder B2- on the plate -20- wherebysaid plate will CIJ be yieldingly urged 'forward toward the work, whileat the same time, the pivotal pin 19- carried by said plate will be heldagainst an adjustable stop-screw 33, which is engaged in a threadedaperture in the inner end oit the support -l0-, Figure 2 so that theitorward urging of Athe plate --20- by the spring i/,ariasee "B 250lwill automatically hold the arms -W-alin contact with theb'earingf'pins -`8- by reason of the tact that the support Q10- isconnected by the piiots v llandlinks lld to both ot the arms-Qrelatively small supplemental carriage -ilis adjustable lengthwise ot"and upon the inner end ot the sliding plate 20; by

means oli' an adjusting screw 35 which is journalednear one end in a lug'-36- on the plate QU- and has its other yend threaded and engaged witha pendent lug -3T- on the under side ot' the supplemental carriage saidscrew being held against endwis'e `movement by suitable collars engagingopposite iaces ot the lug -35-, as shown in Figure A. tool post 3B- ismounted upon the supplemental' carriage 34e-for receiving and supportinga fcutt-ing tool as -39-, which is held in lplace by cla'niping screw-Ow and a bar-417 the latter haring a spherical lower face seated uponthe corresponding sphericaliacc in the upper side ot a bearing washere2-Figures 2 and G, ifvliicli permits'the tool to readily adjust itselfto its seat anda'lsoailords a broad bearingtorthe underside of the'toolto better resist the vibration ot' the tool wheny engaging the work.

The arms -9- are shown 'as adjusted to torni a right angle to cause the'tool -39- to cuta convertr spherical contour upon the work 'nF- whenthe latter is rotated or `(by the substitution of a cutting tool, as

-39-, having a straight vertical cutting edge),` a convex cylindricalcontour il the work is stationary 'ot' la radius 'equal to onehalt thedist-ance between the axes 'of the bearing pins -8', under whichconditions, the straight inner sides l2- o'f thearms 4will be engagedwith ythe flat bearing faces -8-, while the axis oi the pivotal pin 19-connecting the support L10- and slding plate -20- will lvbeat theAvertex et the incliuled angle between the inner ta ccs of the arms adistance from a centralpoint in a direct line between the axis oit thepins -8- at right angles vto said lineequal to the distance between saidcenter and'aXes -ot' tl'ie-'pins so thatthe axes ot said pins and pivot-19-y will represent Athreepoints in the circumference of a `circlehaving a diameter equal to the distance between the airis of the pins*E5- t llow.n il the carriage 2].- wit'li the plate "Q0" thereon ismoved transversely ot the axis. et the work-holder B andthe straightVsides -l2-- of' the arms held in contact with the flat 'faces ot thebearing pins HS-by means of the spring 30-7 it evident that ythe axis otthe pivot w19- at the vertex oil the included angle between the straightsides l2- will describe a true'arc ot circle having'a radius equal toVhalt` oit the'distance between said pins, and that the tool `39 whichtakesth'e same movement as the plate -20- and pivot"-l9- willl describea circular arc ot the same radius yand cause the surface or" the work tobe ,machmed to a circular contour of the same radius. j j i It is `alsoevident from the foregoing desc'ription that it the included anglebetween thestraight sides 12- is increased by the proper adjustment ofthe arms -9- through the medium or" the screw "17e, and the carriage 20-is moved back 'and forth, it will cause the pivot w19-'and cutting pointof the tool -39- to move in arcs of corre-` spondingly increased radii,and that this 4adjustr'ii'ent may be continued until 'the straight sides12- of the arms 9* may "be brought into'the same straight line, underwhich co'nditioifis` the surface jcut by the tool 39n would beacorresponding straight or flat surface.

This adjustment may be continued with the straight sides 12+ still inengagement with the bearing 'pins ''-8- until the angle is reversed toldegreesyas shown by dotted for cut-ting circular faces upon the work ot`widely Varyingradii are'inade by moving the cross-bloclr -'-1- alongits guide yways -c--,` as Jfor example when the angle between the arms-^9w is increased, from a rightangle toward a straight line, it isnecessary to more the cross-'block farther away :from the work to bringthe bearing pins -8- into engagement `with the straight edges l2- or'the arms -9-, this adjustment being continued las the vangle between the`arms is reversed tor producing concave surfaces upon tliewoi'k so thatif the reverse angle should be 90 degrees for cutting a concave surfacehaving a radius equal to haltthe ydistance between the axes of the pins-8-, it would be `necessary to adjust the cross-block -lto the positionshown by dott-ed lines in Figure l in order to bring the bearing pinsinto proper engagement with `the straight edges l2- of the arms 9-providing thesliding plate *2O and work-holder remain in substantiallythe same relative position in which case the pivotal pin -19- wouldremain lin the same position, as 'shown in Figures l land 2, andwill'then be at the vertex ot' the angle, it being understood that incase the anis ot the pivot l9-v should not be exactly in line with saidVertex, it' may be brought into proper alinement by n'ieans of theadjustng "All screw -33-, which would, oi' course, move the slidingplate 20- with or against the spring -30--- In operation, assuming thatthe parts are adjusted to produce a convex spherical or cylindricalsurface, it would be simply necessary to move the carriage -2l* back andforth or transversely of the axis of the work by means of a hand-screw*524.- during which operation, the sliding plate -20- with thetool-holder thereon would be urged toward the work by the spring -30-,and will thereby cause the toolto cut the surface of the work to thedesired contourn The angle between the arms -9- may be increased at willto any desired extent by simply loosening the adjusting-screw IY- whichwould allow the spring E30- to urge the plate M-2O- forwardly or towardthe work to keep the straight edges l2- in contact with the bearing pins--8, it being understood that the cross-block Jimay be adjusted tocompensate for the changed positions of the arms -9- to keep the pins -8in contact with the straight edges -12- it desired, the adjustment ofthe cross-block being effected by hand or by any other suitable means.

What I claim is:

l. In a circular arc forming device, two members having .spaced bearingpoints in one and the same circular arc, a pair of arms havingstraight-edges disposed at an angle to each other and engaging saidbearing-points, the vertex ot' the angle formed by said straightsedgesbeing disposed in the same arc and in a line bisecting said angle, andmeans for holding the arms in fixed relation, said arms beingmovableacross and against the bearing points to cause the vertex of the angleto travel around the circular are.

2. In a circular arc forming device, two members having spaced bearingpoints in one and the same circular arc, a pair of arms havingstraight-edges disposed at an angle lto each other and engaging saidbearingpoints, the vertex of the angle formed by said straight-edgesbeing disposed in the same are and in a line bisecting said angle, meansfor holding the arms in iixed relation, said arms being movable acrossand against the bearing points to cause the ver- `tex of the angle totravel around the circular arc, and yielding means for holding the armsin contact with the bearing points.

3. In a circular arc forming device, two members having spaced bearingpoints in one and the same circular arc, a pair of arms `havingstraight-edges disposedat an angle to each other and engaging saidbearingpoints, the vertex of the angle formed by said straight-edgesbeing disposed in theA same arc andy in a line bisecting said angle,means for holding the arms in fixed relation, said arms being movableacross and against the bearing points to cause the vertex ot the angleto travel around the circular arc, a toolholder, and means fortransmittingparallel motion from the vertex of the angle of said arms tothe toolholder to cause the tool to move in an arc of the same radius asthat of the first named arc. i

el. In combination with a rotary workholder, a carriage movabletransversely of the axis oit the work-holder, a member mounted upon thecarriage to move therewith and having an independent movement lengthwisethereof. a tool-holder mounted on said member to move therewith,yielding means for urging said member in one direction to cause the toolto engage the work, bearing-members arranged in spaced relation equaldistances from and at opposite sides of the produced axis of theworkholder, members having straight-edges disposed at an angle to `eachother and engag ing said bearingmembers, a pivot turning in thc firstnamed member about an axis coincident with the vertex of the anglebetween said straight-edges and movable with said first named member,and connections between said pivot and straight-edge-members to causethe latter to move with the bearing-members located equal distances fromand at opposite sides of the produced axis of the work-holder.straight-edge-members having their straight edges disposed at an angleto each other and engaging said bearing-members, means for adjusting thestraight-edge-members to different angles, means for moving` saidstraight-edge-members lacross their respective bearing-members withoutchanging the angle to which they are adjusted, whereby the vertex ottthe angle between the straight-edges is caused to move in a circulararc, a tool-holder, and means actuated by the .last named means forcausing` the tool-holder to travel in a circular arc of the same radiusas that' through which the vertex ot the angle between thestraight-edges is moved.

' 6. In a circular arc forming device, bearing-members in spacedrelation in the arc of the circle, straight-edge-members having theirstraight edges disposed at an angle to l each other and engaging saidbearingmem- :rasante and in a plane at right angles to the pro-- ducedaxis of the work-holder, a plate mounted upon and movable with theoari'iage and having an independent movement lengthwise thereof, atool-holder mounted upon said plate, a spring Jfor urging the plate inone direction to cause the tool to engage the work, and means torcausing the plate to move longitudinally while being moved transverselyby the carriage.

8. ln combination with a rotary worlrholder, a carriage movable'transversely ot the axis oit the Work-holder, a plate mounti ed uponand movable with the carriage and having an independent movementparallel with said axis, a tool-holder mounted on said plate, means forurging the plate in one direction to cause the tool. to engage theworlr, a member pivoted to said plate to move therewith and having anindependent movement about the axis or' the pivot, bearing-memberssupported equal distances trom and at opposite sides ot' the producedaxis of the worlnholder, straightedge-members having their straightedges disposed at an angle to each other and engaging saidbearing-members, the vertex ot said angle being coincident with the axisof said pivot, and connections between the straight-edgeinembers andsaid pivoted member to cause said straight-edge-members to move with theplate and to have an independent movement about the axis of the pivot. f

9. In combination with a rotary-workholder, a carriage movabletransversely ot the axis of the work-holder, a plate mount ed upon andmovable with the carriage and having an independent movement parallelwith` said axis, a tool-holder mounted on said plate, means tor urgingthe plate in one direction to cause the tool to engage the work, amember pivoted to said plate to move therewith 4and having anindependent movement about the axis ot the pivot, bearing-memberssupported equal distances trom and at opposite sides of the producedaxis of the work-holder, straight-edgemembers having their straightedges disposed at an angle to each other and engaging saidbearing-members, the vertex ot said angle being coincident with the axisol said pivot, connections between the straightedge-members and saidpivoted member to cause the said straight-edge-members to move with theplate and to have an independent movement about the axis of the pivot,and means lor adjusting the straight- `relation with their axes in acircular arc and provided with diametrical bearing-faces,straight-'edge-members having their straight edges disposed at an angleto each other and engaged with said bearing-faces, saidstraight-edge-members being movable across said bearing-faces withoutchanging the angle between the straight-edges to cause the verter: ofthe angle to travel along said circular arc, and means for adjustingsaid straight-edge-members to diterent anglesl to vary the radius of thearc through which the vertex' of the i angle between said straight-edgesmay travel.

l2. in combination with a rotary workholder, bearing-pins spaced equaldistances from and at opposite sides oit the produced axis of thework-holder, straight-edge-mem bers having their straight edges engagingsaid bearing-members, a plate movable transversely of said airis andhaving an independent movement lengthwise thereot, a pivot turnable onsaid plate about an axis coincident with the vertex oi' the anglebetween said straight-edges, connections between said pivot andstraight-edge-members for moving the latter across the bearingmembers,and a tool-holdermounted upon said plate.

ln witness whereof l have hereunto set my hand this 18th day of March,1921.

RAYMOND F. LAFLER. Witnesses H. E. CHASE, M. R. Cooin.

